tiempo - Temporal API datetime utilities

Returns a ZonedDateTime at the first moment of the quarter (1st day of the quarter's starting month at midnight). Quarters: Q1 = Jan–Mar, Q2 = Apr–Jun, Q3 = Jul–Sep, Q4 = Oct–Dec.

Signature

function startOfQuarter(
  input: Temporal.Instant | Temporal.ZonedDateTime
): Temporal.ZonedDateTime
function startOfQuarter(input: Temporal.PlainDate): Temporal.PlainDate
function startOfQuarter(
  input: Temporal.PlainDate,
  timezone: Timezone
): Temporal.ZonedDateTime

A PlainDate with no timezone stays in calendar space and returns a PlainDate. Pass a timezone to bridge a PlainDate into a zoned ZonedDateTime.

Parameters

Parameter	Type	Description
`input`	`Temporal.Instant \| Temporal.ZonedDateTime`	The datetime to get the start of quarter for

Returns

A Temporal.ZonedDateTime at midnight on the 1st day of the quarter (January, April, July, or October).

Examples

import { startOfQuarter } from '@gobrand/tiempo';

const instant = Temporal.Instant.from('2025-05-15T12:00:00Z');
startOfQuarter(instant);
// 2025-04-01T00:00:00Z[UTC]

const zoned = Temporal.ZonedDateTime.from('2025-08-15T15:30:00-04:00[America/New_York]');
startOfQuarter(zoned);
// 2025-07-01T00:00:00-04:00[America/New_York]

// PlainDate in → PlainDate out (no timezone)
startOfQuarter(Temporal.PlainDate.from('2025-05-15'));
// 2025-04-01

Common Patterns

Quarter-to-date

import { startOfQuarter, now } from '@gobrand/tiempo';

const current = now('America/New_York');
const quarterStart = startOfQuarter(current);

// Quarter-to-date range: [quarterStart, current]